The purpose of the Specimen Assessment Core is provision of a centralized resource to the individual projects of the optimal collection and appropriate storage of tissues and biological fluids, performance and analysis of necropsies, measurement of indices relevant to methamphetamine, lentivirus injection, and their technical assistance and economy of scale cost savings for common procedures. For the science in this Program Project, it is crucial to have proper evaluation, handling, and archives of tissues for the investigators' uses. In this manner maximal information may be gained from the evaluation of samples during the life of the animals and from tissues at autopsy, and the use of the tissues, fluids, and cells for a variety of techniques by the investigators will be facilitated. Furthermore the use of common techniques and assays will greatly assist us in making cross-species comparisons of the various markers examined. The Core is designed to provide a broad range of techniques to analyze specimens during the course of the investigators' experiments. The Core is organized around three units: Immunological/Molecular/Pathological assessment. Quantitative Neurotoxicity assessment, and Neurospectroscopic assessment. The Core will process samples, perform necropsies and subsequent histopathological analysis, process samples appropriately for the investigators' experiments, perform quantitative microscopy, proton magnetic resonance spectroscopy, assessment of free radical damage, HPLC analysis of monoamines and their metabolites, and assist the investigators in new assay development. The Core has now begun some of the investigations proposed by the Project PIs, and has generated meaningful data allowing them to start addressing their hypotheses. Having a Core to perform this work will allow the experience, expertise, and centralized storage and dispersal of specimens, greatly facilitating the work of the Program while providing cost savings.